Lubricating oil and anti-wear additives therefor



United States Patent 3,130,161 LUBRICATING OIL AND ANTI-WEAR ADDITIVES THEREFOR Henricus G. I. van der Voort and Maurits Krukziener,

Amsterdam, Netherlands, assignors to Shell Oil Company, a corporation of Delaware No Drawing. Filed Nov. 2, 1959, Ser. No. 850,034

Claims priority, application Netheriands Nov. 1.8, 1958 3 Claims. (Cl. 252-515) This invention relates to improved lubricants and to additives therefor.

Combustion engines such as gasoline engines and diesel engines are more or less subject to Wear of cylinders, pistons and piston rings. In automobile engines, in particular, it is a known phenomenon that considerably increased wear occurs when the cylinder temperature remains relatively low, as is the case when driving short distances. According to the general view, this is due to moisture condensing on the cool cylinder Walls in the presence of acids such as sulfuric acid from sulfurous fuel, hydrohalic acids from lead scavengers, and organic acids from incompletely burnt gasoline. The corrosion caused by these acids, also termed cold corrosion, is responsible for much of the piston and cylinder wear in automobiles.

In order to inhibit wear in combustion engines it has already been proposed to incorporate in the lubricating oil certain additives capable of rendering the said acids harmless by neutralizing them. Examples are oil-soluble neutral or basic organic metal compounds such as calcium, barium or zinc salts of petroleum sulfonic acids, of alkylated hydroxy benzoic acids, and others. In many cases, it has been possible to obtain good results by incorporating such organic metal salts in the lubricating oil.

The use of metal salts, however, is attended by drawbacks. One disadvantage, for example, is the fact that the metal salts formed by neutralization of the acids resulting from the combustion are generally insoluble in oil. This may lead to disturbances, particularly as a result of the formation of deposits in the combustion space which may subsequently cause precombustion.

It has now been found that excellent detergent and wear inhibitors for lubricants are provided by reacting polymerized 1,2-alkylene imines with: (I) a polymer of an olefinic unsaturated monomer (A) having at least one oleophilic group of at least 8 or more carbon atoms and at least one polar group including (11) copolymers of (A) with olefinic unsaturated monomers (B) similar to (A) but not necessarily containing a polar group, and also including (III) telomers of polymers (I) or (II). The reaction products may be represented by the following formula, wherein it will be understood that (A) and (B) are the polymer units from the olefin monomers (A) and (B):

in which R and R are hydrogen atoms or methyl groups, R is an oleophilic group having 8 or more carbon atoms and it may be polar or non-polar, and R is a polar group. R may be an oleophilic group which is similar or dissimilar to R The oleophilic group R preferably contains 1220 carbon atoms. The olefin monomer (B) has the formula:

in which R and R are hydrogen atoms or methyl groups,

R and R are hydrogen atoms, hydrocarbon radicals or polar substituents containing not more than 7 carbon atoms. The 1,2-alkylene radical of the 1,2-alkyleneimine are illustrated by ethylene, propylene, butylene groups or the like and the polar-containing groups contained in the telomeric compounds are illustrated by halogen, mercapto, nitro groups derived from aliphatic or aromatic halohydrocarbons, alkylmercaptans, nitro-alkanes and nitroaromatic compounds, the monoand dinitro benzenes or toluenes being preferred. The degree of polymerization of the alkylene imine and the monomer (A), respectively are such that each unit becomes at least equal to 5, preferably varying from 5 to 25 or higher such as 150. The molecular weight of the reaction product in telomeric form should not exceed 10,000 and preferably should be between 2000 and 5000, and when in non-telomeric form the molecular weight is at least 1000 and preferably from about 80,000 to about 500,000.

The polymerized 1,2-alkylene imines which are used according to the invention and converted with the said telomers and/or polymers or copolymers are preferably polymerization products of ethylene imine and/ or propylene imine, although polymerization products derived from higher C-alkyl ethylene imines, such as 1,2-butylene imine, C-propyl ethylene imine, C-tetradecyl ethylene imine and others, are also suitable. These polymerized alkylene imines may be prepared in a known manner, e.g., by treating the corresponding monomers with small quantities of acid catalysts such as hydrochloric acid as described in the German patent specification 665,791 or by condensation of alkylene dichlorides with a given ammonia as described in US. Patent 2,381,730 or by thermal decarboxylation of 2-oxazolidones. In cases in which the telomers and/ or copolymers with which the alkylene imine polymerization products are to be converted them selves have acid properties, direct use may also be made of these telomers and/ or copolymers in polymerizing by means of acids.

The resultant products generally consist of mixtures of polymerization products of varying degrees of polymerization and may contain either branched-chain or straight chain molecules. Although polymerized 1,2-alkylene imines of any degree of polymerization may be used, products having an average degree of polymerization greater than 5, particularly greater than 25, are preferred. It is unnecessary for the polyalkylene imines employed to be soluble in oil. A suitable product, for example, is Polymin P which is a 40-70% water solution of polyethylene irnine commercially available from Badishe Aniline and Soda Fabrik, A6.

The telomers and/or copolymers suitable for the conversion with polymerized 1,2-alkylene imines are oil-soluble compounds containing at least one polar group. The polar groups may be solely present at ends of the chains or at any desired points in the molecule including the chain ends.

The telomer compound may be imagined as formed by polymerizing or copolymen'zing one or more olefinic unsaturated monomers (A), or such monomers (A) together with one or more olefinic unsaturated monomers (B), in the presence of a telomen'zation agent containing at least one polar group.

The copolymer may be correspondingly derived by copolymerizing a monomer (A) with one or more monomers (B), at least one of the monomers (B) containing one or more polar groups.

Although the said telomers and/ or copolymers are usually obtained in the above-described manner, other methods of preparation are not excluded. It is possible, for example, to start from a polymer, copolymer or telomer in which no polar groups need be present, and to introduce the desired polar groups in a known manner, for instance by substitution. It is also possible to change polar groups already present by chemical reactions, for instance by hydrolysis, exchange, etc.

. By oleophilic groups present in monomer (A) and represented by symbol R are here meant substituents whose presence solubilizes the telomer or copolymer molecules in hydrocarbon media. The said oleophilic groups contain or entirely consist of cyclic and/ or acyclic hydrocarbon radicals having at least 8 carbon atoms. In addition, polar groups and/ or heteroatoms may also occur in the oleophilic groups, provided their presence does not result in the telomer or copolymer becoming insoluble in oil.

Specially suitable oleophilic groups include cyclic hydrocarbon radicals among which may be mentioned, for example, alkaryl groups, particularly alkylphenyl groups such as the p-octylphenyl group. Acyclic hydrocarbon radicals are also important, preferably branched or unbranched aliphatic hydrocarbon chains such as di-isobutyl, dodecyl, tetradecyl and hexadecyl groups.

The oleophilic groups may also contain polar groups, e.g.,

and/or heteroatoms such as O in addition to the above-mentioned cyclic and acyclic hydrocarbon radicals. Particularly important in this connection are oleophilic groups represented by such groups as ?OR5, fiNH-R5, ({1R5 in which R represents a substituted or non-substituted hydrocarbon radical. The R group is generally a cyclic or acyclic hydrmarbon radical which may or may not be substituted by polar groups and/ or heteroatoms, although a branched or unbranched alkyl group, such as the lauryl, tri-isobutyl, hexadecyl and stearyl group, is preferred.

Suitable (A) monomers include olefins, particularly such alpha-olefins as decene and cetene styrene derivatives, such as aralkyl styrenes, e.g., para-octyl styrene and ardodecyl alpha-methyl styrene; ethers such as propenyl 2-ethylhexyl ether and vinyl octadecyl ether; esters of alkenols and carboxylic acids, preferably aliphatic carboxylic acids, e.g., vinyl stearate, allyl palmitate and methallyl oleate; esters of unsaturated acids and alcohols derived from such acids as acrylic acid, methacrylic acid, maleic acid, fumeric acid, the crotonic acids, citraconic acid and cinnamic acid, e.g., lauryl and stearyl (meth)- acrylate, dihexadecyl maleate, diodecyl citraconate; and acid amides, such as hexadecylmethacrylic acid amide.

Very good results are obtained when the monomer (A) is an alkyl ester of acrylic acid or methacrylic acid. Lauryl methacrylate and stearyl methacrylate have been found particularly suitable, although in a very advantageous embodiment of the invention use is made of mixtures of lauryl methacrylate and stearyl methacrylate for example, since the lubricating oil additives produced there With act as pour point depressants with regard to the unmixed components.

The hydrocarbon radicals may be cyclic and/ or acyclic, e.g., tolyl, cyclohexyl, benzyl as well as branched or unbranched alkyl and alkenyl groups such as methyl.

By polar substituents which may be present in monomer (B) and represented by symbols R and R include nonmetallic atoms of groups V to VII of the periodic table, e.g., nitrogen, phosphorus, oxygen, sulfur and chlorine, in particular nitrogen and oxygen, or groups containing such atoms; the said atoms and groups may or may not form part of or be bound to hydrocarbon radicals. Examples of the said groups are XR, -CXXR, -NO CN, SCN, NR

4 in which X=oxygen or sulfur and R=hydrogen or a hydrocarbon radical.

Examples of very suitable polar substituents are hydroxyl, carboxyl, cyano and amino groups. Another important type contains a tertiary amino group in the form of a heterocyclic nitrogen-containing group such as a pyridine group or a pyrrolidone group. Among the polar substituents are here also included such substituents as w, fi l0: %|3 1o,' OR10 in which R represents a substituted or unsubstituted hydrocarbon radical. Care should be taken to ensure that the entire polar substituent does not contain more than 7 carbon atoms. In the case of a group such as COR the R group should, therefore, not contain more than 6 carbon atoms. Suitable substituents of this type are represented by the group in which the hydrocarbon radical R is preferably substituted by one or more hydroxyl and/ or amino groups, particularly the -(IZIlOCHZ-CH OH OH and (EOCHZ-OHZN(CQH5)Q groups.

Suitable (B) monomers include olefins, e.g., propylene, 1- or Z-butylene, di-isobutylene and others, and aromatic hydrocarbons such as styrene, although use is preferably made of acids, e.g., maleic acid or the anhydride thereof, particularly methacrylic acid; of alcohols such as vinyl alcohol and allyl alcohol; of pyridine derivatives such as Z-methyl-S-vinyl pyridine, and of pyrrolidone derivatives such as N-vinyl-alpha-pyrrolidone. Esters and amides of acrylic acid and methacrylic acid, ethers and esters of enols such as vinyl alcohol and allyl alcohol, and others, are also suitable. Esters having such groups as in which the R substituent contains one or more hydroxyl and/ or amino groups, have also been found particularly valuable. Use is preferably made of beta-hydroxy ethyl methacrylate and beta-diethyl amino ethyl methacrylate.

Very suitable telomers and/or copolymers for the conversion with polymerized 1,2-alkylene imines according to the invention are derived from lauryl methacrylate and/ or stearyl methacrylate on the other hand, and methacrylic acid and/or beta-hydroxy ethyl methacrylate on the other.

Suitable telomerization agents are the substances usual for this purpose such as mercaptans, chloroalkanes, e.g., carbon tetrahalides, organic nitro compounds and others. Very suitable are aromatic nitro compounds such as nitro benzene which, if desired, may also contain other polar groups, such as p-nitrothiophenol.

The telomer group according to the invention is produced by polymerizing or copolymerizing together with one or more (B) monomers one or more (A) monomers in the presence of a telomer such as an aromatic nitro compound. Especially suitable combinations of the (A) and (B) monomers are mixtures of lauryl methacrylate and/ or stearyl methacrylate on the one hand and methacrylic acid and/or beta-hydroxy ethyl methacrylate on the other.

According to the invention the polymerization products of 1,2-alkylene imines may be converted with the said oilsoluble telomers and/or copolymers by contacting the components, preferably in the liquid phase in a homogeneous medium. The polymerized 1,2-alkylene imine is generally employed as a solution in an organic solvent which, if desired, may also contain water. Suitable solvents are in particular alcohols having from 1 to 4 carbon atoms, e.g., methanol, ethanol, isopropanol and the butanols as well as mixtures thereof with water and/ or hydrocarbons. The hydrocarbons are, for example, gasoline fractions or benzenoid hydrocarbons. The telomers and/ or copolymers are preferably also used as a solution in an organic solvent. Suitable solvents for this purpose are hydrocarbons, e.g., gasoline fractions or aromatic hydro pizirbons such as benzene, toluene, the xylenes, and the In another embodiment of the invention the polymeric alkylene imines are reacted in situ even during the copolymrization or telomerization with the resultant copolymers.

In an advantageous embodiment of the invention a solution of a polymerized 1,2-alkylene irnine in a water/isopropanol mixture is contacted with a solution of one or more telomers and/ or copolymers in toluene, after which the solvents are removed by distillation, if desired, under reduced pressure. It should be observed that both the conversion and the separation of the final product are effected in a particularly simple manner. Especially as compared with the above-mentioned preparation of metal salts, it is an important advantage that no operations such as filtering or centrifuging are required, since in this case it is only necessary to remove solvent, and this may be done by distillation.

The reaction is generally carried out at temperatures in the range of from 20 C. to 130 (3., although higher or lower temperatures are also possible.

It has been found that lubricants in which are incorporated the products obtained according to the invention have excellent weaninhibiting properties. This applies in particular to the inhibition of the wear of pistons, piston rings and cylinders, which occurs in engine cylinders, e.g., in combustion engines such as automobile engines, diesel engines and aero piston engines. Since the starting telomers and copolymers incorporated in lubricants generally have a fairly high detergency with respect to the cylinder fouling in engines in such cases the conversion with the polymerized 1,2-alkylene imines results in products having in addition to detergent properties also wear inhibiting properties.

The said products are suitable as additives to lubricants of various types. In the first place may be mentioned mineral lubricating oils of diverse viscosity, although the products are also suitably incorporated into synthetic lubricating oil as well as into lubricating oils containing fatty oils. The products may also be worked up in lubricating greases.

The products may be added as such to the lubricant. In an advantageous embodiment the product is only partly freed from the solvent and/ or telomerization agent, e.g., by steam distillation; a small quantity of a lubricating oil is then added and the remnants of the solvents and/or telomerization agents are finally distilled off by steam, preferably under reduced pressure. The resultant concentrate may now be diluted with a lubricating oil and/ or worked up into a lubricating grease.

The quantity of the products of the invention incorporated into lubricants may vary within wide limits. In general the desired improvement is already obtained when the quantity incorporated lies between 0.5 and 5%, particularly between 1 and 3% based on the weight of the finished lubricant. In special cases, however, quantities even greater than the said quantities may be incorporated, e.g., in the case of diesel engines in which use is made of fuel having a high sulfur content.

Specific examples illustrating the preparation of additives of this invention are as follows:

EXAMPLE I The starting material was a copolymer of stearyl meth- 0 acrylate and methacrylic acid in which the monomers were present in a molar ratio of 7: 1.

46.5 parts by weight of the said copolymer were dissolved in 435 parts by weight of toluene. 11.25 parts by weight of Polymin P (an approximately 70% by weight aqueous solution of polyethylene imines), diluted with 157 parts by weight of isopropanol, were then added with stirring and heated to 50-60 C. Part of the isopropanol was then removed from the reaction mixture by means of a Dean and Stark apparatus, the same volume of a Venezuelan mineral lubricating oil (viscosity: 114 cs. at 100 F.) being simultaneously added. The maximum temperature during this operation was C. Approximately 500 parts by weight of the said lubricating oil were then added and the remaining solvents distilled off in vacuo (0.3 mm. Hg) at 75 C.

A clear concentrate was obtained which was diluted with the said lubricating oil to 3000 parts by weight. The lubricating oil thus prepared, which contained 1.75% by weight of the additive, was used for the engine tests given below.

EXAMFLE II The starting material was a copolymer of stearyl methacrylate, beta-hydroxy ethyl methacrylate and methacrylic acid in which the monomers were present in a molar ratio of 10:2:1.

50 parts by weight of this polymer were dissolved in 260 parts by weight of a mixture of benzene and toluene (ratio by volume 1:1). 14.5 parts by weight of Polymin P (an approximately 70% by weight aqueous solution of polyethylene imines), diluted with 80 parts by weight of isopropanol, were then added at room temperature in one batch. The resultant clear solution was then heated over a. steam bath for approximately 15 minutes using a reflux condenser. 500 parts by weight of a Venezuelan mineral lubricating oil (viscosity: 114 cs. at F.) were then added and the solvents distilled off in vacuo (0.3 mm. Hg) at 75 C.

The resultant concentrate was diluted with the said lubricating oil to 3860 parts by weight. The lubricating oil thus prepared, which contained 1.55% by weight of the additive, was used in the engine tests given below.

EXAMPLE III The starting material was a telomer prepared by copolymerizing stearyl methacrylate and beta-hydroxy ethyl methacrylate in the presence of nitrobenzene, and in which the two monomers were present in a molar ratio of 5:1.

A solution of 73 parts by weight of the said telomer in 870 parts by weight of toluene was heated to approximately 70 C. 19.5 parts by weight of Polymin P (an approximately 70% by weight aqueous solution of polyethylene imines), diluted with 235 parts by weight of isopropanol, were added in a single batch. The resultant clear solution was then heated over a steam bath for approximately 15 minutes using a reflux condenser. 2000 parts by weight of a Venezuelan mineral lubricating oil (viscosity: 114 cs. at 100 F.) were then added and the solvents distilled off in vacuo (0.3 mm. Hg) at 75 C.

The resultant concentrate was diluted with the said lubricating oil to 5200 parts by weight. The lubricating oil thus prepared, which contained 1.66% by Weight of the additive, was used in the engine tests given below.

EXAMPLE IV The starting materials were:

(1) 350 parts by weight of a solution of 70 parts by weight of stearyl methacrylate, 5.5 parts by weight of beta-hydroxy ethyl methacrylate and 0.8 part by weight of dodecyl mercaptan in benzene, and

(2) A solution of 7.5 parts by weight of anhydrous polyethylene imines in 240 parts by weight of a mixture of isopropanol and benzene (ratio by volume 4:1).

The two solutions (1) and (2) were mixed by stirring, in a clear and homogeneous mixture being obtained. This mixture was then heated, using a reflux condenser, and passing through nitrogen, while stirring, and 0.5 part by weight of azodiisobutyric acid nitrile was added, followed by an equal quantity of azodi-isobutyric acid nitrile after 1 /2 hours, the mixture being boiled for a total of 18 hours.

180 parts by weight were then removed by distillation, the residue cooled to room temperature and subsequently decanted into 1580 parts by weight of methanol of C. The resultant precipitate was then centrifuged off and taken up in 350 parts by Weight of benzene. The purification was repeated by subjecting the latter benzene solution to the same methanol treatment. The resultant precipitate was taken up in 300 parts by weight of henzene, after which 55 parts by Weight of a white powder were isolated by freeze-drying. The nitrogen content of this powder was 0.36% by weight.

Engine Tests Engine tests carried out in a CRF gasoline engine with the doped lubricating oil which contained products prepared according to the Examples I to III showed a considerable reduction in ring wear.

The fuel used was a motor gasoline which had a sulfur content of 0.06% and contained 0.7 ml. TEL per US. gallon. The temperature of the cooling water was 40 C. The figures in the following table show the ring wear in mg. of iron in experiments of 45 hours. The ring wear relates to all four piston rings.

TABLE A [Additive amount: 1.5% wt. of copolymer plus 0.025 lug/g.

oil of polyethylene imine] Venezuelan mineral lubricating oil lr'aving a viscosity of 11 1 cs. at 100 F.

SMAzstearyl methacryI-a'te; HEMAzbeta-hydroxy ethyl methacrylate; MA=methacry1ic acid.

In their use the present products may also be combined with other additives such as anti-oxidants, detergent dopes, viscosity-index improvers, corrosion inhibitors, anti-foaming agents, pour point depressants, extreme pressure and oiliness agents and other materials generally added to lubricants.

We claim as our invention:

1. An, improved mineral lubricating oil composition comprising a major amount of mineral lubricating oil and, from about 0.5% to about 5% by weight of an oilsoluble reaction product of a polymerized 1,2-alkylene imine having from 5 to 150 imine units with a polymer of a mono-olefinic monomer containing an acidic polar group selected from carboxyl and hydroxy groups and an oleophilic hydrocarbyl group of from 8 to 18 carbon atoms, said reaction product having a molecular Weight of from 1000 to 500,000.

2. An improved mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 5% by Weight of an oilsoluble reaction product of polymerized 1,2-alkylene imine having from 5 to imine units and a copolymer of free methacrylic acid and a C alkyl acrylate ester, the acid portion of the ester being selected from the group consisting of acrylic acid and methacrylic acid, the molecular weight of the total product being from 80,000 to 500,000.

3. An improved mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 5% by Weight of an oilsoluble reaction product of polymerized 1,2-alkylene imine having from 5 to 150 imine units and a copolymer of a hydroxy alkyl acrylate and a C alkyl acrylate ester, the acid portion of said C ester being selected from the group consisting of acrylic acid and methacrylic acid, the total molecular weight of the product being from 80,000 to 500,000.

4. An improved mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 5% by Weight of an oilsoluble reaction product of polymerized 1,2-alkylene imine having from 5 to 150 imine units and a copolymer of free acrylic acid and a C alkyl acrylate ester, the acid portion of the ester being selected from the group consisting of acrylic and methacrylic acid, the total molecular weight of the product being from 80,000 to 500,000.

5. An improved mineral lubricating oil composition of claim 3, wherein the copolymer is in the form of a telomer formed by a telomerizing agent selected from the group consisting of haloalkane, alkyl mercaptan, nitro alkane, and nitrobenzene, the molecular weight of the telomer ranging from 1000 to 10,000.

6. An improved mineral lubricating oil composition comprising a major amount of mineral lubricating oil and about 0.5% to about 5% by weight of an oil-soluble reaction product of polyethylene imine having from 5 to 25 imine units and a copolymer of stearyl methacrylate and methacrylic acid in the mol ratio of 7:1, respectively, said product having a molecular Weight of from 80,000 to 500,000.

7. An improved mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 5% by Weight of an oilsoluble reaction product of polyethylene imine having from 5 to 25 imine units and a copolymer of stearyl methacrylate, beta-hydroxy ethyl methacrylate and methacrylic acid in the mol ratio of 10:2:1, respectively said product having a molecular Weight of from 80,000 to 500,000.

8. An improved mineral lubricating oil composition comprising a major amount of mineral lubricating oil and from about 0.5% to about 5% by weight of an oil-soluble reaction product of polyethylene imine having from 5 to 25 imine units and a nitrobenzene telomer of a copolymer of stearyl methacrylate and beta-hydroxyethyl methacrylate in the mol ratio of 5:1, respectively, said product having a molecular weight of 1000 to 10,000.

References Cited in the file of this patent UNITED STATES PATENTS 2,296,225 Ulrich Sept. 15, 1942 2,440,800 I-Ianford et al May 4, 1948 2,628,941 Adelson et al Feb. 17, 1953. 2,839,512 Barnum et al June 17, 1958- 2,870,129 Merriam Jan. 20, 1959 2,889,282 Lorensen et al June 2, 1959, 2,892,788 Stewart et al June 30, 1959 FOREIGN PATENTS 466,270 Great Britain May 24, 1937 760,554 Great Britain Oct. 21, 1956 OTHER REFERENCES The Condensed Chemical Dictionary, Fifth Edition, 1956, Reinhold Publishing Corp., New York, pages 18 and 19 pertinent. 

1. AN IMPROVED MINERAL LUBRICATING OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL AND FROM ABOUT 0.5% TO ABOUT 5% BY WEIGHT OF AN OILSOLUBLE REACTION PRODUCT OF A POLYMERIZED 1,2-ALKYLENE IMINE HAVING FROM 5 TO 150 IMINE UNITS WITH A POLYMER OF A MONO-OLEFINIC MONOMER CONTAINING AN ACIDIC POLAR GROUP SELECTED FROM THE CARBOXYL AND HYDROXYL GROUPS AND AN OLEOPHILIC HYDROCARBYL GROUP OF FROM 8 TO 18 CARBON ATOMS, SAID REACTION PRODUCT HAVING A MOLECULAR WEIGHT OF FROM 1000 TO 500,000. 